Device and process for marking molded items and tablets with laser beams

ABSTRACT

Process and device for applying markings (9) and/or providing break notches on moulded items or tablets (4) by means of laser beams. The installation (16) which produces the laser beam (3) is arranged on a tablet-producing press, to which it is functionally connected by synchronization systems (18). A deflection system (17) is arranged on the die support (5) of the press in order to deflect the laser beam (3) onto the surface of the moulded item or tablet (4). The laser (16) is provided with an optical system (15) having interchangeable masks provided with openings through which the laser beam passes (3).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a process and a device for marking moldeditems, tablets with monochrome or polychrome symbols, letters, numbersor break notches by applying the desired markings with the aid of apulsed laser beam, the laser being arranged directly in atablet-producing press.

The marking of solid forms of drugs is a necessity, in order to preventthe risk of confusion during manufacture and distribution, and to enablea rapid identification, for example in connection with cases ofpoisoning. It is for this reason, for example, that diverserecommendations or statutory requirements (GMP, among others) exist inmany countries of the World. The manufacturers of solid drugs aredutybound to manufacture the latter in such a way that the risk ofconfusion is minimal as early as during the process of manufacture. Useof the above markings could further increase safety in this area.Monochrome or polychrome marking of molded items and tablets is possibleby more than one process.

2. Description of the Related Art

A known process for the marking of tablets is the dying of the pressingmixture and/or stamping with stamping tools specially manufactured forthe purpose. The disadvantages of this manufacturing process are ahigher expenditure on development and more complicated formulae becauseof the dye distribution and/or stamping. Additional problems areoccasioned by legal restrictions on the use of dyes, which are notalways internationally uniform, and by the machine performance, which,due to the use of stamping tools, is not always as desired. In addition,depending on the stamping, the stamping tools are much more expensivethan pressing tools in the absence of stamping. In addition, theformulae pressed with a stamping punch require a more intensive, ie.also a more expensive development, and the use of special auxiliarymaterials, because with the use of stamping punches, tablet formulaewhich can be pressed without a problem using normal, curved or planepunches can give rise to considerable difficulties depending on thenature of the stamping. Also in use are a number of processes forprinted markings and, for example, an ink marking process, the so-calledink-jet printing system, is described in U.S. Pat. No. 4,548,825. In allthese processes, the tablets are printed in a specially developedapparatus only once they have been manufactured, which means that thecost of the preparation is substantially increased. Moreover, duringmanufacture or intermediate storage, the risk of confusion mentionedabove could well always be there. Another common process is the coatingof tablets with films of different colors, the advantage being that allstampings, break grooves, etc. remain visible. The tablets to befilm-coated must have a certain minimal curvature, which is importantfor the rolling movement in the coating apparatus. The disadvantage isthat with curvature or additional stamping, the tablets become moredifficult to press. In general, the film tablets require a considerablyhigher expenditure on raw material and development than does the tabletmarking by dyeing the pressing mixture. It is also possible tosugar-coat tablets, but here, too, only biconvex molded items arecapable of being sugar-coated well and the stampings and break grooveson the molded item or dragee core are covered over by the drageecoating, and so do not remain visible. Disadvantages are the longmanufacturing period and the associated uneconomic nature of themanufacture of dragees.

The marking of tablets with the aid of lasers is fundamentally known(U.S. Pat. No. 3,657,510) and Defensive Publication T 903,014). However,both processes lack a system for the exact alignment of the tablets tobe marked.

Even assuming that such apparatuses already exist for use in the markingof tablets, there remains the intermediate storage of the tablets to bemarked after pressing and thus the risk of confusing tablets of similarappearance before or during the marking process.

SUMMARY OF THE INVENTION

It is the object of the invention to organize the marking of moldeditems and tablets in a safer fashion and to exclude confusions and falsemarkings.

This object is achieved by arranging the system which generates thelaser beams, also known simply as the laser, on a tablet-producing presswith which it forms a unit. The laser is arranged in such a way that thespecially guided laser beam operates on the material to be marked eitherfrom the side or from above the tablet while it is still on the lowerpunch in the die, doing so directly after the pressing process or as thetablet is ejected or in a special tablet alignment. The achievementaccording to the invention is a process for applying markings and/orproviding break notches on molded items or tablets by treating thesurface with a laser beam, in which process the treatment takes placegenerally coterminously with ejection of the molded item or the tabletfrom the die of a tablet-producing press. Preferably, this comprisesdeflecting the laser beam onto the top of the molded item or the tablet.In another embodiment, the laser beam is deflected onto the side face ofthe molded item or of the tablet, and the the (sic) treatment is carriedout at the moment at which the molded item is ejected from the die bythe lower punch as far as above the upper edge of the former. In orderto be able to apply different markings, the form of the marking isproduced by a mask arranged in the laser beam and having openings in theform of the desired marking.

The invention also includes a device for applying markings and/orproviding break notches on molded items or tablets by means of laserbeams using an installation to generate a laser beam, an installation togenerate a laser beam (sic) which is arranged on a tablet-producingpress, to which it is functionally connected by synchronization systems,and a deflection system, which is arranged on the die support of thetablet-producing press in order to deflect the laser beam onto thesurface of the molded item or tablet.

The installation for generating the laser beam is preferably a gaslaser. The installation for generating the laser beam is provided withan optical system having interchangeable masks, through whose openingsthe laser beam passes. The deflection direction (sic) can be arrangedand aligned by the side of the die support in such a way that the laserbeam runs parallel to the surface of the die support in the direction ofthe vertical axis of the die. Alternatively, the deflection system isarranged and aligned at the side of the upper punch of thetablet-producing press in such a way that the laser beam strikes the topof the molded item or tablet before the center of the molded item ortablet has been displaced horizontally from the vertical axis of thedie. If eccentric presses are used in place of rotary presses, it ispreferred to provide systems to move the deflection system back andforth from a position by the side of the upper punch into a positionabove the die, in order to be able to apply the marking on the top ofthe molded item. It should be stressed in this connection that a specialalignment device can be replaced by time synchronization of the laseremployed with the tablet-producing press and the path followed by thetablet as dictated by the tablet-producing press.

The synchronization of the operating cycle of the tablet-producing presswith the laser is such that the treatment of the surface of the moldeditem with the laser beam takes place after completion of the pressingprocess and the withdrawal of the upper punch from the die. Depending onthe deflection of the laser beam, the latter strikes the top of themolded item while the latter is still located in the die, or while it isbeing ejected from the die, as long as the molded item is only beingmoved vertically, but not horizontally.

However, the synchronization can also be arranged so that anappropriately deflected and aligned laser beam strikes the side of themolded item immediately after vertical ejection from the die.

Apart from the various signs, letters etc. applied to the surface of themolded items, it is also possible to apply markings laterally onto theedges. Moreover, partial notches or break notches can be produced ontablets.

If molded items or tablets having different colored layers are treatedwith the laser beam for marking purposes, the different colored layerscan be burned out layer by layer depending on the desired makeup of themarking as to color and pattern.

It follows that application of the system can replace the conventionalmarking of molded items by means of stamping tools, which offersconsiderable advantages, such as, for example, savings on stampingtools, since by changing the signs or lettering of the laser it ispossible to use the same pressing tool to provide any number ofpreparations with a distinguishing mark, but also savings on developmentwork for formulae, since the expensive formulae required for stampingtools are not necessary.

A commercial gas or solid-state laser can be arranged on thetablet-producing press, particular preference being given to carbondioxide, excimer or YAG lasers. In this process the laser beam can beapplied using two different methods (laser marking system). On the onehand, the laser beam can be guided through a mask, whose openingscorrespond to the signs to be reproduced. On the other hand, the laserbeam is focused on the molded item or tablet to be marked and reproducesthe desired signs with the aid of a computer program. The carefullyfocused laser beam, guided with the aid of, for example, glass fibers ormirrors onto the surface of the tablet, then forms the desired signs bymelting, bleaching, vaporizing, oxidizing etc. the surface of thetablet. If necessary, the beam guide can be mobile and synchronized withthe movement of the parts of the tablet-producing machine by, forexample, a telescopic or swivelling movement. The laser beam isintensity-modulated, so that the focused laser energy writes or printsthe word or symbol to be used onto the tablet. It should be emphasizedin this connection that this technique is not confined to tablets, butcan be applied to molded items of the most varied materials orcompositions, such as, for example, molded items of any shape made fromvarious plastics, metals and other pressable materials from the fieldsof chemistry, foodstuffs, electronics, inter alia, for example, controlbuttons, catalysts, ceramic components and the like.

A further advantage of the system according to the invention is the factthat by changing the laser computer program or the writing masks it iseasy to interchange the symbols, letters or numbers to be stamped.

Additional advantages relate to an economic and efficient production,since the laser writing can be carried out with polished and unpolishedtablets, be cause surface dust on tablets poses no problem in relationto the production of a clear inscription. It follows that the system issuitable for higher production speeds in a clean process, and can, inaddition, be used for the marking of uneven, curved and otherwise shapedsurfaces.

The arrangement of the system according to the invention will now befurther described with the aid of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional side view of a first embodiment ofthe present invention,

FIG. 2 is a partial cross-sectional side view of a second embodiment ofthe present invention;

FIG. 3 is a partial cross-sectional side view of a third embodiment ofthe present invention;

FIG. 4 is a partial cross-sectional side view of the first embodiment ofthe invention;

FIG. 5 is a top view of the first embodiment of the present invention;

FIG. 6 is a partial cross-sectional side view of a fourth embodiment ofthe present invention;

FIG. 7 is a partial cross-sectional side view of a fifth embodiment ofthe present invention;

FIG. 8 is a partial cross-sectional side view of a sixth embodiment ofthe present invention;

FIG. 9 is a plan view of a seventh embodiment of the present invention;

FIG. 10 is a partial cross-sectional side view of the seventh embodimentof the present invention;

FIG. 11 is a photograph of a tablet marked in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENTINVENTION

FIG. 1 shows a diagrammatic representation of the system according tothe invention, in which a laser 16 is arranged on a tablet-producingpress and is functionally connected to it via a synchronizing component18. The tablet-producing press is provided with a mobile upper punch 1running in an upper punch guide 2, a mobile lower punch 6 running in alower punch guide 7, between which is located the die table 5 with a die10. Shown diagramatically inside the die is a molded item 4, to whichthe laser beam 3 produced by the laser 16 is directed, in order toeffect a marking generally coterminously with ejection of the moldeditem 4 from the matrix 10.

FIGS. 2 and 3 show the arrangement of an optical system 15, providedwith a plurality of interchangeable marking masks, in the laser beam 3,which by means of a mirror 8 in the beam deflection system 17 isdirected onto the molded item 4, in order to carry out the marking 9 atthe very moment that the molded item 4 is ejected from the die 10 of arotary press of conventional design the lower punch 6 moving in thepunch guide 7. The tablet-producing press is provided on a circulartrack of the die disk 5 with a number of dies 10, in which the lowerpunch 6 and the upper punch 1 running in the upper punch guide 2 engage,in order to form the molded item 4. For safety reasons, the laser beam 3runs inside protective tubes 14. The laser beam 3 is generated by alaser 16, not shown in the figures, arranged on the tablet-producingpress. In FIG. 2, the deflection system 17 is located next to the diedisk, in order to direct the laser 16, either from below if the laser isarranged beneath the die disk 5, as shown, or from above if the laser isarranged above the die disk 5 (not shown), onto the side edge of themolded item 4, so that a marking 9 is produced on the edge of the moldeditem 4.

In FIG. 3 the laser is arranged to the side above the die disk 5, andthe deflection system 17 with the mirror 8 is arranged directly next tothe upper punch 1, so that the laser beam 3 strikes the top of themolded item 4 at the moment of ejection from the die or, as the case maybe, also immediately prior thereto, and produces a marking 9 at thatlocation.

In order to apply different markings, the optical system 15 is designedso that marking masks with openings in the form of the desired markingcan be arranged in the laser beam 3. When the product is changed, only achange of the marking mask is required.

FIGS. 4 and 5 show the device for marking tablets or molded itemsaccording to the invention in the form of a rotary tablet-producingpress, the laser 16 being arranged next to the body of the machine 11and having an optical system 15 such that the laser beam 3 runs in theprotective tube 14 parallel to the surface of the die disk 5 at adistance from the surface. The deflection system 17 with its mirror 8,which is located at the end of the protective tube 14, is placed in thecircuit of the dies 10 above a stop position of the die 10 after thepressing process, but before the ejection of the molded item 13. Thishas the advantage that marking can take place on the entire surface ofthe molded item 4, and the deflection system 17 and pressing tools,through being arranged at different locations on the circuit of the die10, within the die disk 5, do not spatially interfere, and facilitatethe subsequent fitting out of existing presses 16 with the opticalsystem 15 and deflection system 17, the pressing tools being the mobileupper punch running in the guide 2 and the mobile lower punch running inthe guide 7, which engage in the die 10.

However, the design according to the invention can also be embodied withso-called eccentric presses. The arrangement of laser 16, optical system15 and, as the case may be, deflection system 17 is representeddiagramatically in FIGS. 6 to 10. A known design of an eccentric pressincludes within the body of the machine 11 a die 10 located in the dietable 5, in which during the pressing process the upper punch 1 andlower punch 6 engage to form a molded item 4. Punches 1 and 6 run backand forth in guides 2 and 7. The filling of the die 10 with material isdone via a filler 19 which is displaceable on the surface of the dietable 5, and, at the same time, conveys sideways to the ejecting device13 arranged at an angle on the edge of the die table 5 the molded item 4ejected from the die 10 by the lower punch 6. Upon return of the filler,the press is prepared for the next pressing process. With eccentricpresses it is particularly advantageous to use optical glass fibers withan appropriate optical system as protective tubes 14 for guiding thelaser beam 3, as shown in FIG. 6. The mobility of the glass fibers makespossible an arrangement of the end of the glass fiber optics immediatelynext to the upper punch 1 in such a way that the laser beam strikes thetop of the molded item 4 to produce a marking 9. Alternatively, it isalso possible, as shown in FIG. 8, to arrange a deflection system 17with a mirror 8 next to the upper punch, in order to direct the laserbeam 3 onto the top of the molded item 9, when the latter is ejectedfrom the die 10 by the lower punch 6. However, it is also possible, asshown in FIG. 7, to arrange the deflection system 17 with mirror 8 atthe side of the guide table 5 a little above the surface, so that thelaser beam 3 strikes the side edge of the molded item 4 and produces amarking 9 on its edge. It is also possible in principle, by designingthe deflection system 17 to move back and forth, to bring it cyclicallyinto a position beneath the upper punch 1 above the molded item 4, sothat the laser beam 3 strikes the molded item 4 vertically from above,as shown in FIGS. 9 and 10. Given appropriate synchronization of themovements of upper punch 1, lower punch 6 and deflection system 17, thelaser beam marking of the molded item 4 can take place still within thedie 10, but also during the ejection process, as long as the molded itemis still located beneath the deflection system 17 moved into its markingposition, or in the area of the laser beam 3. The mobility of thedeflection system 17 can be achieved, for example, using protectivetubes 14, which are telescopically displaceable into one another andwhich are moved synchronously with the operating cycles of the press bymeans of an appropriate system not shown in the Figures.

FIG. 9 shows a plan view and FIG. 10 a sectional view of such anembodiment of the design of an eccentric press.

FIG. 11 is a photograph of a tablet marked according to the invention onthe top with two numbers, and it shows that depressions are produced inthe surface by the laser beam, which represent visible and legiblemarkings.

Example Preparation of placebo cores for markings with CO₂ -laser

In principle, a number of positions in the tablet-producing machine aresuitable for the laser marking of tablets. In this case, the positionwas chosen where the tablets are still located in the die of the rotaryplate, directly before ejection from the die. The synchronization of thelaser pulses was produced by electronic connection between thetablet-producing press and the laser.

1. Composition

    ______________________________________                                                                  per lot, 10 kg = 30,300                                                       cores weighing                                      Raw Material     per core 330.0 mg each                                       ______________________________________                                        1. Lactose D 80 Ph.Eur II                                                                      80.00 mg 8,000.00 g                                          2. Maize starch Ph.Eur.I                                                                       10.00 mg 1,000.00 g                                          3. Gelatine DAB 8                                                                              3.00 mg  300.00 g                                            4. Distilled water                                                                             27.00 mg 2,700.00 g                                          5. Maize starch Ph.Eur.I                                                                       6.00 mg  600.00 g                                            6. Magnesium stearate                                                                          1.00 mg  100.00 g                                            Ph.Eur.II                                                                     ______________________________________                                    

2. Preparation procedure

8,000.0 g of lactose D 80 and 1,000.0 g of maize starch are sieved witha 1.0 mm Frewitt sieve and then granulated with the warm solution of300.0 g gelatine in 2,700.0 g water in a WSG UD 5 fluidized-bedgranulator at an inlet air temperature of about 50°-60° C. Aftersubsequent sieving with a 1 mm sieve, the granular material produced ismixed with a proportionately calculated amount of maize starch andmagnesium stearate. The pressing mixture thus obtained is pressed withthe aid of the Horn RP 16 H tablet-producing press into tablets havingthe following parameters:

    ______________________________________                                        tablet weight     330.0 mg                                                    tablet diameter    10.5 mm                                                    tablet radius of curvature                                                                       9.5 mm                                                     appearance        round biconvex film tablet                                                    cores                                                       color             white                                                       disintegration time                                                                             about 10 mins.                                              (in H.sub.2 O)                                                                friability        max. 0.3% after 10 min.                                     tablet hardness   about 80 N                                                  ______________________________________                                    

3. Marking

Directly after being pressed, the tablets were marked in thetablet-producing machine with the aid of a CO² (sic) laser. The markingwas applied in the form of the number "56" in the outer layer of thesurface of the tablet. During the process, the tablet-producing machinetook on the function of an alignment device.

I claim:
 1. A process for applying markings or break notches on moldeditems or tablets, said process comprising:treating a surface of a moldeditem or tablet with a laser beam, said treatment being generallycoterminous with ejection of the molded item or tablet from a die of apress.
 2. The process for applying markings or break notches on moldeditems or tablets as claimed in claim 1, further including deflectingsaid laser beam onto the top of said molded item or tablet.
 3. A devicefor applying markings or break notches on molded items or tablets bymeans of a laser beam, comprising:an installation which generates alaser beam, said installation for generating the laser beam beingarranged on a tablet-producing press and being connected to saidtablet-producing press by a synchronization system; and a deflectionsystem arranged on a die support of said tablet-producing press todeflect said laser beam onto the surface of the molded item or tablet.4. The device for providing markings or break notches on molded items ortablets as claimed in claim 3, wherein said installation for generatingsaid laser beam is a gas laser.
 5. The device for applying markings orbreak notches on molded items or tablets as claimed in claim 3, whereinsaid installation for generating said laser beam is provided with anoptical system including a plurality of interchangeable masks, saidinterchangeable masks including openings through which said laser beampasses.
 6. The device for applying markings or break notches on moldeditems or tablets as claimed in claim 3, wherein said deflection systemis arranged and aligned at the side of said die support such that saidlaser beam runs parallel to the surface of said die support towards avertical axis of a die.
 7. The device for applying markings or breaknotches on molded items or tablets as claimed in claim 3, wherein saiddeflection system is arranged and aligned at the side of an upper punchof said tablet-producing press such that said laser beam strikes the topof said molded item or tablet before the center of the molded item ortablet has been displaced horizontally from a vertical axis of a die. 8.The device as claimed in claim 3, including systems to move saiddeflection system between a position at the side of an upper punch and aposition above a die.
 9. A process for applying markings or breaknotches on molded items or tablets by treating a surface of a moldeditem or a tablet with a laser beam, said process comprising:deflectingsaid laser beam onto the side face of the molded item or tablet, saidtreatment being generally coterminous with ejection of said molded itemor tablet from a die of a press, said treatment occurring when themolded item or tablet is ejected above the upper edge of the die by alower punch.
 10. A process for applying markings or break notches onmolded items or tablets, comprising:treating a surface of a molded itemor tablet with a laser beam, said treatment being generally coterminouswith ejection of the molded item or tablet from a die of a press;wherein the shape of said marking or break notch is produced by amarking mask arranged in the path of the laser beam, said marking maskhaving openings in the shape of the desired marking or break notch.